If you count OS X as a desktop operating system, Unity has pretty much a traditional desktop. The Dash resembles the dock, search resembles Spotlight, and toplevel menus are all familiar.
The Quantal Quetzal beta already ran very stable on my machine, but I did run into in issue where every time I start Google Chrome (Win key, 'chrome') I get directed to an Software Centre 'page' about Google Chrome. I can only start Chrome by pressing Winkey + A, and then typing 'chrome'.
Also, the Show/Hide Desktop was in the Alt-Tab, which is annoying, because you'll accidentally hide all apps every now and then. This is old behaviour, but can be disabled in 12.10 now: